Tsunamis are rare, powerful and unpredictable natural hazards, with devastating consequences for coastal populations caught in their path. The vast majority are caused by earthquakes in active seismic areas and occur along a limited range of inhabited shores around the world (Figure 1). In total, 16 major tsunamis killed 250,900 people in 21 countries between 1996 and 2015, according to EM-DAT records.